Hearing aids are used to assist patients suffering hearing loss by transmitting amplified sounds to ear canals. In one example, a hearing aid is worn in and/or around a patient's ear. Patients generally prefer that their hearing aids are minimally visible or invisible, do not interfere with their daily activities, and easy to maintain. One difficulty in providing such hearing aids is associated with power supply. The battery of a hearing aid occupies a substantial portion of the device and/or requires frequent replacement. Use of a rechargeable battery reduces the cost and replacement frequency associated with a non-rechargeable battery. Cordless charging technology provides the patient with an easy way to recharge the hearing aid. However, the rechargeable battery and its charging circuitry present a significant challenge in the minimization of the hearing aid. The cordless charging, while convenient to operate, may require a charging circuitry of significant size in the hearing aid and/or a lengthy period for the battery to be fully recharged. Thus, there is a need for providing a hearing aid with a power supply that is small, efficient, and easy to maintain.